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101.
Inoue K Sakamoto T Yuge S Iwatani H Yamagami S Tsutsumi M Hori H Cerra MC Tota B Suzuki N Okamoto N Takei Y 《Molecular biology and evolution》2005,22(12):2428-2434
Natriuretic peptides (NPs) are a group of hormones playing important roles in cardiovascular and osmoregulatory systems in vertebrates. Among the NP subtypes, atrial NP (ANP), B-type NP (BNP), and ventricular NP (VNP) are circulating hormones expressed exclusively in the heart (cardiac NPs). The constitution of cardiac NPs is variable among species of vertebrates. In order to understand the evolutionary and functional significance of such variation, we performed a systematic survey of cardiac NP cDNAs in nine taxonomically diverse teleosts inhabiting environments of varying salinity. The discovery of the coexistence of the ANP, BNP, and VNP genes in the eel and rainbow trout suggested that the ancestral teleost had all three cardiac NPs. As the VNP cDNA was undetectable in ayu and six species of Neoteleostei, it is possible that VNP was lost before the divergence of Osmeroidei. The ANP gene was also undetectable in the medaka. Thus, only the BNP gene is universal in species examined in the present study. Synthetic medaka BNP preferentially activated two medaka GC-A-type receptors, suggesting that the three cardiac NPs share the same receptor. However, the regulation of BNP expression may be the most strict because ATTTA repeats in the 3'-untranslated region and the dibasic motif in the ring are conserved among teleosts and tetrapods. Linkage analyses in the rainbow trout located ANP, BNP, and VNP genes on the same chromosome, which suggested the generation of the VNP gene by tandem duplication as observed with ANP and BNP genes. If the duplication occurred before the divergence of tetrapods and teleosts, VNP may exist in the tetrapod lineage. 相似文献
102.
Jun Ohwada Sawako Ozawa Masami Kohchi Hiroshi Fukuda Chikako Murasaki Hitomi Suda Takeshi Murata Satoshi Niizuma Masao Tsukazaki Kazutomo Ori Kiyoshi Yoshinari Yoshiko Itezono Mika Endo Masako Ura Hiromi Tanimura Yoko Miyazaki Akira Kawashima Shunsuke Nagao Eitarou Namba Koutarou Ogawa Nobuo Shimma 《Bioorganic & medicinal chemistry letters》2009,19(10):2772-2776
CH0793076 (1) is a novel hexacyclic camptothecin analog showing potent antitumor activity in various human caner xenograft models. To improve the water solubility of 1, water-soluble prodrugs were designed to generate an active drug 1 nonenzymatically, thus expected to show less interpatient PK variability than CPT-11. Among the prodrugs synthesized, 4c (TP300, hydrochloride) having a glycylsarcosyl ester at the C-20 position of 1 is highly water-soluble (>10 mg/ml), stable below pH 4 and rapidly generates 1 at physiological pH in vitro. The rapid (ca. <1 min) generation of 1 after incubation of TP300 with plasma (mouse, rat, dog and monkey) was also demonstrated. TP300 showed a broader antitumor spectrum and more potent antitumor activity than CPT-11 in various human cancer xenograft models. 相似文献
103.
Toba S Gibson TM Shiroguchi K Toyoshima YY Asai DJ 《Cell motility and the cytoskeleton》2004,58(1):30-38
An important challenge is to understand the functional specialization of dynein heavy chains. The ciliary outer arm dynein from Tetrahymena thermophila is a heterotrimer of three heavy chains, called alpha, beta and gamma. In order to dissect the contributions of the individual heavy chains, we used controlled urea treatment to dissociate Tetrahymena outer arm dynein into a 19S beta/gamma dimer and a 14S alpha heavy chain. The three heavy chains remained full-length and retained MgATPase activity. The beta/gamma dimer bound microtubules in an ATP-sensitive fashion. The isolated alpha heavy chain also bound microtubules, but this binding was not reversed by ATP. The 19S beta/gamma dimer and the 14S alpha heavy chain could be reconstituted into 22S dynein. The intact 22S dynein, the 19S beta/gamma dimer, and the reconstituted dynein all produced microtubule gliding motility. In contrast, the separated alpha heavy chain did not produce movement under a variety of conditions. The intact 22S dynein produced movement that was discontinuous and slower than the movement produced by the 19S dimer. We conclude that the three heavy chains of Tetrahymena outer arm dynein are functionally specialized. The alpha heavy chain may be responsible for the structural binding of dynein to the outer doublet A-tubule and/or the positioning of the beta/gamma motor domains near the surface of the microtubule track. 相似文献
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106.
Dongsu Choi Yoko Watanabe Robert D. Guy Tetsuto Sugai Hiroto Toda Takayoshi Koike 《Acta Physiologiae Plantarum》2017,39(3):71
Key message
The black locust is adapted to elevated [CO 2 ] through changes in nitrogen allocation characteristics in leaves.Abstract
The black locust (Robinia pseudoacacia L.) is an invasive woody legume within Japan. This prolific species has a high photosynthetic rate and growth rate, and undergoes symbiosis with N2-fixing micro-organisms. To determine the effect of elevated CO2 concentration [CO2] on its photosynthetic characteristics, we studied the chlorophyll (Chl) and leaf nitrogen (N) content, and the leaf structure and N allocation patterns in the leaves and acetylene reduction activity after four growing seasons, in R. pseudoacacia. Our specimens were grown at ambient [CO2] (370 μmol mol?1) and at elevated [CO2] (500 μmol mol?1), using a free air CO2 enrichment (FACE) system. Net photosynthetic rate at growth [CO2] (A growth) and acetylene reduction activity were significantly higher, but maximum carboxylation rate of RuBisCo (V cmax), maximum rate of electron transport driving RUBP regeneration (J max), net photosynthetic rate under enhanced CO2 concentration and light saturation (A max), the N concentration in leaf, and in leaf mass per unit area (LMA) and ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCo) content were significantly lower grown at elevated [CO2] than at ambient [CO2]. We also found that RuBisCo/N were less at elevated [CO2], whereas Chl/N increased significantly. Allocation characteristics from N in leaves to photosynthetic proteins, NL (Light-harvesting complex: LHC, photosystem I and II: PSI and PSII) and other proteins also changed. When R. pseudoacacia was grown at elevated [CO2], the N allocation to RuBisCo (NR) decreased to a greater extent but NL and N remaining increased relative to specimens grown at ambient [CO2]. We suggest that N remobilization from RuBisCo is more efficient than from proteins of electron transport (NE), and from NL. These physiological responses of the black locust are significant as being an adaptation strategy to global environmental changes.107.
Coevolution of the S-locus genes SRK,SLG and SP11/SCR in Brassica oleracea and B. rapa 总被引:1,自引:0,他引:1
Sato K Nishio T Kimura R Kusaba M Suzuki T Hatakeyama K Ockendon DJ Satta Y 《Genetics》2002,162(2):931-940
Brassica self-incompatibility (SI) is controlled by SLG and SRK expressed in the stigma and by SP11/SCR expressed in the anther. We determined the sequences of the S domains of 36 SRK alleles, 13 SLG alleles, and 14 SP11 alleles from Brassica oleracea and B. rapa. We found three S haplotypes lacking SLG genes in B. rapa, confirming that SLG is not essential for the SI recognition system. Together with reported sequences, the nucleotide diversities per synonymous and nonsynonymous site (pi(S) and pi(N)) at the SRK, SLG, and SP11 loci within B. oleracea were computed. The ratios of pi(N):pi(S) for SP11 and the hypervariable region of SRK were significantly >1, suggesting operation of diversifying selection to maintain the diversity of these regions. In the phylogenetic trees of 12 SP11 sequences and their linked SRK alleles, the tree topology was not significantly different between SP11 and SRK, suggesting a tight linkage of male and female SI determinants during the evolutionary course of these haplotypes. Genetic exchanges between SLG and SRK seem to be frequent; three such recent exchanges were detected. The evolution of S haplotypes and the effect of gene conversion on self-incompatibility are discussed. 相似文献
108.
109.
Although many estimations have been made electronically of mammalian sperm volume, detailed investigations have not been reported for avian spermatozoa with an electronic counter. In the present study, sizing of spermatozoa of fowls and Muscovy and Pekin drakes was examined using a Coulter counter (model ZB). In our preliminary work on fowl sperm volumes, we found mono- or di-morphic distribution displays that were modified depending on the combination of amplification (AMP) and aperture current (APC). Therefore, methodology to estimate the fowl and drake sperm volume was examined. Dilution of semen had no effect on the dimorphic distribution pattern of the sperm volume. Density-gradient centrifugation did not separate two kind of particles in the semen in either continuous or discontinuous Percoll gradients; therefore, we varied settings of AMP and APC, and found that the most suitable settings for measuring sperm volumes of these birds are 1 for AMP and 8 for APC. With these settings, mean volumes of spermatozoa were 5.1 μm3 for fowls, 5.7 μm3 for Muscovy drakes, and 5.6 μm3 for Pekin drakes. 相似文献
110.
Ueki Y Shoji M Suto A Tanabe T Okimura Y Kikuchi Y Saito N Sano D Omura T 《Applied and environmental microbiology》2007,73(17):5698-5701
The fate of calicivirus in oysters in a 10-day depuration was assessed. The norovirus gene was persistently detected from artificially contaminated oysters during the depuration, whereas feline calicivirus in oysters was promptly eliminated. The prolonged observation of norovirus in oysters implies the existence of a selective retention mechanism for norovirus within oysters. 相似文献